Imagine the situation in which we don't have any physical money and every currency is digitalized. The US dollar is now a token, the Japanese Yen is only in the network and the British pound is a fast-moving digital coin. What are the consequences of such an economy for the poorest of the population? Do you think that a few people can influence the digital wealth of people and wouldn't hackers be the best people to have as friends?
That's actually not good for any economy because the GDP of the economy will be affected very badly when it would be compared to an economy which only uses physical coins. Most of the economists consider crypto as a transfer income which again is not used when national income or GDP is calculated. And poor people will find it really hard to use cryptos as they might have not even used a computer before and they don't such facilities as well.